The result -- fewer heroine addicts, fewer drug-related crime, less active criminal underworld (because of lower drug-related income).
An adult discourse and proper handling of addiction and substance abuse not only helps the addicts, but the whole society.
Giving away the addictive thing you still have to pay the societal cost of having people addicted to it. Switzerland handles this is a very admirable way and they have excellent outcomes, due to treating addiction as a disease rather than an individual moral failing.
I don't see why substance abuse in particular should get a super-special treatment in our discourse on human addiction-related behavior.
If it's destroying your ability to function in society, and something that you might want to drop the habit of, we should support our fellow people in doing it. If that is gambling, video-games, porn, they all activate similar dopamine related effects. Heroine and other opiates are super-effective at this, but it is still the same pathway being activated.
This issue isn’t really the money -> gratification conversion, it’s the addictive nature of the process. If I’ve done everything I can to addict you to my product (to remove your ability to decide for yourself)... I’m in a morally bad area.
I’m of the opinion that some of these addictive response patterns should be banned from games flat-out, whether or not there’s a direct connection to someone’s line of credit.
If heroine were free, it would still be a problem for those addicted to it, if not for very long. (Although no one would have a financial incentive to get other people hooked, so it’s an interesting thought experiment as to whether use would increase or decrease).